For is used for a period of time (three hours, two weeks, eight months etc)
He has been living in this village for ten years.
Since is used for a start of a period. (8 o'clock, Wednesday, 1999 etc)
He has been reading this book since Monday.
He has been living in this village for ten years.
Since is used for a start of a period. (8 o'clock, Wednesday, 1999 etc)
He has been reading this book since Monday.